Apparatus for protection of electronic circuits

Abstract

The invention relates to an apparatus ( 1 ) for protection of electronic circuits with a decentralized power supply (PS 1 , PS 2 ). One object of the invention is to avoid damage to other loads (PN 1 , PN 2 ) which are still intact when a short circuit occurs in one load (PN 1 , PN 2 ) in the circuit. The apparatus ( 1 ) comprises a number of loads (PN 1 , PN 2 ) which are supplied in a decentralized manner. One monitoring device (PSUP 1 , PSUP 2 ) in each case monitors a respective one of the load supply voltages (P 1 , P 2 ) and ensures primary-side fault disconnection of all the power supplies (PS 1 , PS 2 ) if a threshold value is undershot.

What is claimed is:  
     
       1. An apparatus for protection of electronic circuits comprising : 
       a first and a second power supply;  
       a first and a second load associated with the first and the second power supply;  
       a monitoring circuit for monitoring at least one of the first load, the second load, the first power supply and the second power supply;  
       a first switch, associated with at least one of the power supplies for switching on and off the at least one power supply, a second switch for primary side fault disconnection of the at least one power supply; and  
       a second switch for primary-side fault disconnection of the at least one power supply,  
       an optocoupler with at least an optical transmitter; and  
       a first resistor coupled with a controllable diode, the first resistor having a resistance such that a holding current holds the controllable diode active if the optical transmitter is switched off.  
     
     
       2. The apparatus of  claim 1 , wherein an output voltage from the first and/or from the second power supply is monitored by the monitoring circuit. 
     
     
       3. The apparatus of  claim 1 , wherein the monitoring circuit is supplied from the first and/or from the second power supply. 
     
     
       4. The apparatus of  claim 1 , wherein the monitoring circuit is supplied in a redundant manner from the first and from the second power supply. 
     
     
       5. The apparatus of  claim 1 , wherein the monitoring circuit comprises a first and a second monitoring device, associated with the first and the second power supply, respectively. 
     
     
       6. The apparatus of  claim 1 , further comprising a logic device associated with the monitoring circuit and/or the monitoring circuit transmits control signals to the logic device. 
     
     
       7. The apparatus of  claim 6 , wherein the logic device associated with the first and the second monitoring device and/or the first and the second monitoring device transmit control signals to the logic device. 
     
     
       8. The apparatus of  claim 1 , wherein the first and/or the second power supply is associated with a voltage source. 
     
     
       9. The apparatus of  claim 1 , wherein the second switch is associated with the monitoring circuit and/or can be switched by means of a signal which is transmitted by the logic device. 
     
     
       10. The apparatus of  claim 1 , wherein the second switch comprises conductive decoupling. 
     
     
       11. The apparatus of  claim 1 , further comprising a third monitoring device associated with the logic device and/or transmits control signals to the logic device. 
     
     
       12. The apparatus of  claim 11 , wherein the third monitoring device is supplied in a redundant manner from the first and the second power supply. 
     
     
       13. The apparatus of  claim 11 , wherein the third monitoring device comprises supply means for a signal which can be transmitted to the logic device. 
     
     
       14. The apparatus of  claim 11 , wherein case during switching on, the third monitoring device is coupled to a signal to be monitored with a time delay with respect to the first and/or the second monitoring device. 
     
     
       15. The apparatus of  claim 1 , further comprising: 
       a number of power supplies;  
       a number of loads, each load being associated with a power supply; and  
       a monitoring circuit for functional monitoring of the loads and/or of the power supplies, wherein case the power supplies can be controlled and/or can be switched off by means of the monitoring circuit.  
     
     
       16. The apparatus of  claim 15 , wherein the monitoring circuit is supplied in a redundant manner from essentially all the power supplies.